As mentioned above, servers keep rotating nowadays. You could be using same DNS but still get different server. Servers are distributed / scattered around the world for almost for all big companies. They all use CDN (content delivery network)
You also have to test your speed using same website like
www.speedtest.net or
www.fast.com, etc. You shouldn't use game download server for comparison. Game download servers' speed is always non predicable, even same server. they can always limit (adjust) download speed on the fly.